Some time back people were trying to get custom made lids for their Snow Peak mugs. Four Dog Stove Company has them in stock again for the 450, 600, 700, 900 and 1400. Some are available in either aluminum or titanium, with or without drain holes. Donald does not have the order form for these lids on the web-site, but you can contact him via the web page at www.fourdog.com . I ordered a titanium lid for my Snow Peak 900 and it fits perfect. I have not field tested it yet but I assume it will be fine.